Privacy is becoming a major industry concern as more wireless transmit/receive units (WTRUs) are connected directly or indirectly to the Internet. Ubiquitous connectivity, together with poorly secured protocol stacks and a lack of privacy education of many users makes it easy to track/monitor the location of users and/or eavesdrop on the users' activity. Many factors contribute to this phenomenon, such as the vast digital footprint that users leave on the Internet (e.g., sharing information on social networks, cookies used by browsers and servers to provide a better navigation experience, connectivity logs that allow the tracking of a user's layer-2 (L2) or layer-3 (L3) address, and the like) and/or weak (or even null in some cases) authentication and encryption mechanisms used to secure communications.
Internet privacy has also become an important topic after several recent incidents of widespread and pervasive Internet surveillance have been revealed. Users have become aware of the fact that their communications, habits, and routines may be followed without their consent by different commercial, criminal, and governmental organizations. This issue has created mistrust of the Internet and may affect the acceptance of Internet technology.
For example, a device, and its associated owner, may be tracked by observing the device's Layer-2 (L2) and/or Layer-3 (L3) address communications. L2 addresses may be observed by a third party. The third party may be the operator of the access infrastructure, a passive device listening to communications in the same network, for example over-the-air transmissions performed by 802.11 Wi-Fi devices, and the like. In an 802.11 network, a station (STA) may expose its L2 address in various situations. For example, when a STA is associated with an access point (AP), the L2 address is used in frame transmission and reception, as one of the addresses used in the address fields of an 802.11 frame. In another example, when a STA actively scans for available networks, the L2 address is used in probe request frames sent by the STA.
Traditional L3 address assignment techniques, such as the Internet Protocol version 6 (IPv6) stateless auto-configuration techniques (SLAAC), generate the interface identifier (IID) of the address from its L2 address (via the 64-bit Extended Unique Identifier (EUI-64)), which then becomes visible to all peers with an active IP communication. This visible IID allows for the tracking of a device at L3. The prefix part of the address may also generally provide the physical location of the device, which together with the L2 address-based IID, allows for global device tracking.
Privacy cannot be completely provided by a single communication layer in isolation, as open hooks in other layers may affect the user's privacy overall. The use of temporary addresses, opaque IIDs or even the use of random L2 addresses (as some operating systems do when performing active scanning), may partially mitigate the privacy threat, however these techniques do not completely address all privacy issues.
Privacy concerns affect all layers of the protocol stack, from the lower layers involved in actual access to the network (e.g., the L2/L3 addresses can be used to obtain the location of a user) to the application layers, especially when browsing or getting involved with social networks (e.g., cookies may be used to find out the identity of a user accessing a particular webpage or website).